Cutting Weight 101 (for Athletes)

Nathan Lambert
9 min readFeb 10, 2019

You’re an athlete that needs to get down XXX pounds in YYY days? Can I do it and am I risking my own health?

UFC is the premier location for weight cutting in the modern world. My former nutritionist at Cornell University, Clint Wattenberg, is now the Director of Sports Nutrition at the UFC Performance Institute. That’s probably the highest job that a weight cut expert can get, and he definitely deserves it. Recent news in the area was TJ Dillashaw’s ‘huge’ cut down to 125 pounds. He cut 29 pounds in 12 weeks (mostly water weight), which is remarkable. So how does someone like TJ Dillashaw do it? This guide will walk through steps that my teammates and I used to comfortably cut 5–6% body weight in a week.

TJ went crazy for this weigh in. I bet he turned the knobs on what I am going to outline to the max. Of course the amount of weight he cut is purely wild, but he also hit weight before going to bed the night before a 900am weigh in window. If you’re just getting into cutting weight, or browsing, let’s just say I can’t think of a worse level of discomfort. At this point in the weight cut your brain pretty much doesn’t work (forget why you sat down to eat after getting some milk) and you can lose a lot of bodily function.

The scale is your square of truth.

If you do the weigh in right you’ll have a negligible reduction in ability. For Cornell Lightweight Rowing, we did practice weigh ins followed by recorded tests in training cycles and we would regularly have personal bests following a practice weigh in. Use the weigh in as a tool to get an upper hand on your competitors — let it limit them and unshackle your performance. This guide should be comprehendible for anyone with a background in endurance training — by no means do you need a degree in biology to do this right, that’ll just explain the mechanisms.

Philosophy of a Clean Cut

Food weight: A tool for minimizing water.

The two main targets of the diet changes around a weight cut are 1) minimizing food weight and 2) minimizing water storage via food.

The first goal is simple and clear to even the uneducated athletes weighing in — eat less — but this often results in athletes eating salads and other light foods. We want less total food mass while operating at an elite level, so we want calorie dense foods, which is the opposite of salad. Below I will refer to the ‘fiber cut’ which is eliminating the low calorie high fiber foods, which is mostly your leafy greens, other vegetables, and some starches, check the nutrition facts.

Go to foods for a weight cut process— low carb, high protein, high fat. Yes, eating only peanut butter for a day is acceptable. (Caution: Greek Yogurt is mostly water, so don’t eat that once you’ve cut water, and you want unsalted peanut butter)

Everyone knows the human body is some super high percentage water. For every gram of muscle glycogen your body holds onto 3–4grams of water. The relationship between sodium and water weight is not as strict, but reducing sodium has a clear relationship to lower body weight. In order to minimize weight we want to run on simple low sodium, low sugar foods (this is the time where I would expect the most bang for your buck as being a partially fat-adapted athlete ; check out my profile for a soon to come article on fasting for busy college athletes and young adults). For good foods pre weigh in, search ‘low glycemic index,’ some examples include: eggs, nuts, full-fat greek yogurt, unseasoned meats. This refers to foods that will not spike your blood sugar and there are many solid resources on the matter for the diabetic population.

Water weight: The key for cutting weight.

We want to prepare our body to rapidly get rid of water and then re-ingest it post hitting the scale. The broad strokes picture (more below) is to get the system processing water fast and then shut off to zero water. We see that when you go from fast water processing to zero intake, the body will act like a hose that had high flow rate, it’ll keep excreting water and your weight will drop fast, and safely.

For example, normal lightweight rowing athletes (~6ft tall, 160lbs) will have ~2000 calories of muscle glycogen on hand and ~400 calories of glycogen in their liver. Those 2000 potential calories of carbohydrates would be about 500grams of glucose and 2000grams of water, 4.4pounds. This, and dehydrating the other cells in the body will be the main source of pounds dropped in a weight cut.

Timing: The Risk of Being ‘At Weight’

The time when athletes are at weight but waiting around is the reason weight cuts get a bad wrap in all levels of athletics (youth, collegiate, professional). When you time a weight cut right you will spend less than an hour at weight. Optimal for me was probably 15 minutes at weight, as I know I can sweat out about a pound per 15 minutes, but I would have wiggle room to hit the weight I need. When cutting early (like TJ Dillashaw), athletes spend hours or even close to a day at weight, which can have lasting damage on metabolism and other bodily processes (on top of the pain and suffering sitting at weight). If you spend enough time at weigh ins you will eventually see athletes pass out performing simple tasks trying to get the last tenths of a pound.

Note: I agree that youth athletes should not be required to cut weight. The lack of information, nutritionists, monitoring, etc available creates a huge risk for little reward.

Refueling: Electrolytes then Protein then Carbs

After a weigh in, your body is extremely depleted in multiple areas, and the ordering of re-fueling matters. Here’s my recommended process and why:

  1. Drink an entire Pedialyte (the pediatric rehydration solution). Pedialyte has a medically designed balance of electrolytes, sugar, and water to maximally rehydrate the body. Other solutions like Gatorade tend to have too much sugar. Nuun tablets are also popular, but I promise you’ll see good results transitioning from Gatorade to Pedialyte.
  2. Get a protein shake, protein bar, or other quick protein fix in. For the sweat out the body is training at a high intensity in a low fuel state. The protein will help recovery and prevent muscle degradation after (likely) being in an extended calorie deficit.
  3. Eat some real food. Whatever you like, look for a balance of starches, greens, meats, etc — just make sure you get a decent load of fiber in there to help the gut get back up to speed.
  4. Optional — I would recommend a light workout about 30–60 minutes after refueling. This, almost magically, helps flush the system of junk from the weigh in process. 30 minutes of light cardio will leave the system feeling fresh. The first time I did this I was blown away with the result — it only applies to weigh in’s with events the next day though.

Misconceptions & Mistakes

Philosophy: you want to minimize time close to your target weigh in weight. When you are this light, your body is prone to injury and sickness.

Every time you cut weight too slowly, you are putting your body in a calorie deficient state where it attempts to hold onto water and food. In my experience, I’ve seen that this response only gets worse the more you severely tax your system by not trusting the process. I encourage anyone to do a practice weigh in with a new method, but always trust the process.

Common Mistakes:

  1. Cutting water too early.
  2. Eating high fiber, low calorie foods.
  3. Not being accountable to weights you CAN make.
  4. Not over-hydrating pre-water cut.
  5. Re-fueling with improper food.


To start, here is a rough figure showing how your weight will fluctuate during the week up to a weigh in. Below is details for the different sections. You want to follow the blue line below, a smart setup followed by an incisive cut, weigh in, and recovery. The red is someone worried about weight that cuts too early.

The key to a good cut is resisting the urge to start the cut early. Look to stay around a normal wake up weight until a day or two before the weigh in.

Weight Management Phase (weeks out):

Far out from the scale you really just want to put yourself in a position for success. The key fact is that 3500 calories equates to one pound of metabolized fat in humans. If you’re trying to make your cut a little easier, lose 1 pound a week with a 500 calorie deficit a day, or 1.5 pounds with a 750 calorie deficit. Note, losing more than 1.5% of body weight per week for an extended period of time is dangerous and causes lasting metabolic deficiency.

Pre-Cut Phase (far–5 days out):

Eat clean here. Don’t overdo sodium or sugary foods, but there is flexibility. Use this time to get a clear read on where your wake up weight actually is. This is often the last few days you can hit an easy calorie deficit.

Fiber & Sodium Cut (5–1 days out):

Eliminate your salads and sandwiches (both deli meats and breads tend to be loaded with salt). This period turns into eating simple foods such as plain omelettes with a little cheese and grilled chicken. Towards the end of the fiber cut you will be down a couple pounds as your intestinal track clears out. (Remember not to salt your food, it’s always a mini-disaster when you throw away your almost cooked dinner).

Half way through the Fiber and Sodium Cut you should really hit the water hard. Drink too much. I would put down a couple hundred ounces of water a day on top of that needed for training. You’re doing it right if you have to go to the restroom every 15 minutes. At this time I would also enter a lower carb diet and higher calorie density foods. You can get 2000 calories of peanut butter in about half a pound.

Water Cut (1–0 days out):

Cut water about 18 hours before the weigh in. This means 0 drinking and no watery foods like fruit. From here you will want to match the amount of calories you expect to burn by the weigh in (about 1700 if resting) with only foods such as peanut butter. Calorie density is not the only requirement — low glycemic index is also key. A diet of only peanut M&M’s, while tasty and seeming viable, will spike your blood sugar and make your body balloon with the little water that is left. Toss on an extra layer or two and drift until you have to sweat out.

An hour or two before the weigh in check in with how many pounds you have left. A ~2% weight cut is normal to end off the process in the last day. At 155 lbs I would sweat out a pound per 10 minutes or so once ‘warmed up.’ It will likely take you about 10 minutes to get the sweat going, depending on the exercise, room temp, and clothing choice. I would recommend wearing a non-breathable base layer (think raincoat) with warm layers on top. This base layer can cut the sweat out time by a half. Work backwards from when you want to make weight to start your sweat out, and make sure to leave ~20 min of wiggle room.

Cutting water late will also let the body rebound substantially faster.

Recovery Phase (Pre-Competition):

Follow the details above on refueling, but make sure your urine is clear before you go to sleep. Humans tend to be able to process about 48oz of water an hour, so don’t overdo it on fluids too quick.

I would encourage a strong preference to real, unprocessed food following a weigh in to maximize performance. You can expect to be back up to a few pounds above your wake up weight by the time you go to bed post weigh in.

Below is a summary chart of what I went through.

Summary of a weight cut of 3–4% of normal wake up weight from rowing at Cornell. Weigh in at 500pm on Friday afternoon, pre Saturday morning race.


Weighing in is, in my opinion, one of the fairest way to regulate a competition. It has gotten a lot of negative press during my time in the area — mostly due to athletes working hard to make weight without a good foundation of knowledge. I’ve heard of competitors sitting in a sauna, wearing a trash bag, to sweat out the night before a race. This kind of image is what universities crack down on, and for good reason. I don’t blame the un-informed, I just hope to create a healthier environment. I hope to see sports like wrestling, lightweight rowing, and mixed-martial arts continue to use it.

I hope this article reaches some athletes who do not have the benefit of a top-tied nutrition coach. Thanks for reading and feel free to reach out if you’re interested in more! More on practical sports-nutrition to come.



Nathan Lambert

Trying to think freely and create equitable & impactful automation @ UCBerkeley EECS. Subscribe directly at More at